Earthquake · reviewed by a seismologist
M 5.6mw
6km SSW of Petrolia, CA
- When
- Magnitude
- M 5.6 (mw)
- Depth
- 9.4 km below the surface
- Felt
- 1778 reports · strongest reported intensity VII
- Measured shaking
- intensity VII (ShakeMap)
- USGS impact alert
- green
- Tsunami
- USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
- Nearest
- Humboldt County, 58 km NNE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 279 days ago
This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 1778 people have reported feeling it to USGS.
How big was it?
This earthquake released about 3.5 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.6 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 48× the energy of this one
- Mineral, Virginia 2011 M 5.8 2.1× the energy of this one
- Magna, Utah 2020 M 5.7 1.5× the energy of this one
- This earthquake M 5.6 about 3.5 kilotons of TNT
- Around the size people start to feel M 3.0 this one released 7,400× more
Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.
Where
Epicentre 40.2735, -124.3003. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction | |
|---|---|---|---|
| Humboldt County, CA | 58 km (36 mi) | SSW of here | earthquakes near Humboldt County |
| Trinity County, CA | 109 km (67 mi) | WSW of here | earthquakes near Trinity County |
| Mendocino County, CA | 119 km (74 mi) | NW of here | earthquakes near Mendocino County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
59 earthquakes have been recorded within 50 km since this one.
- 1.5 11km WSW of Petrolia, CA
- 1.6 4km NNE of Petrolia, CA
- 2.3 25km W of Petrolia, CA
- 2.3 36km WSW of Ferndale, CA
- 2.4 6km WNW of Ferndale, CA
- 1.9 24km W of Petrolia, CA
- 2.0 5km NW of Redway, CA
- 1.6 8km W of Petrolia, CA
- 2.4 16km NW of Petrolia, CA
- 2.3 17km WSW of Petrolia, CA
- 1.7 5km N of Ferndale, CA
- 1.6 4km SSW of Petrolia, CA
- 2.7 32km W of Petrolia, CA
- 1.9 5km E of Redway, CA
- 2.4 4km NNW of Petrolia, CA
Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.
For this area
The largest earthquake within 50 km in our catalogue was M 4.7 on 2018-03-23.
From the QuakeIndex catalogue, built from the USGS FDSN event service.
On USGS
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.